1.
A PRACTICAL THEORY OF
LANGUAGE-INTEGRATED QUERY
WITH QUILL
JULIANO ALVES
@vonjuliano

2.
@vonjuliano

3.
@vonjuliano

4.
@flaviowbrasil
https://github.com/getquill/quill

5.
A PRACTICAL THEORY OF LANGUAGE-
INTEGRATED QUERY
@vonjuliano
http://homepages.inf.ed.ac.uk/slindley/papers/practical-theory-of-linq.pdf

6.
SCYLLA – FAILURE
CHARYBDIS – AVALANCHE
@vonjuliano

7.
@vonjuliano

8.
@vonjuliano

9.
RESTRICTIONS
SINGLE DB
RETURNS A FLAT RELATION TYPE
ONLY KNOWN OPERATIONS
@vonjuliano

10.
SELECT w.NAME,
w.age − m.age,
FROM couples c,
people w,
people m
WHERE c.her = w.NAME
AND c.him = m.NAME
AND w.age > m.age
@vonjuliano

11.
quote {
for {
c <- couples
w <- people
m <- people
if (c.her == w.name &&
c.him == m.name &&
w.age > m.age)
} yield {
(w.name, w.age - m.age)
}
}
@vonjuliano

12.
quote {
for {
c <- couples
w <- people
m <- people
if (c.her == w.name &&
c.him == m.name &&
w.age > m.age)
} yield {
(w.name, w.age - m.age)
}
}
@vonjuliano

13.
FlatMap(Entity(Couple,None,List()),Ident(c),FlatMap(Entity(Per
son,None,List()),Ident(w),Map(Filter(Entity(Person,None,List()),
Ident(m),BinaryOperation(BinaryOperation(BinaryOperation(Pr
operty(Ident(c),her),==,Property(Ident(w),name)),&&,BinaryOp
eration(Property(Ident(c),him),==,Property(Ident(m),name))),&
&,BinaryOperation(Property(Ident(w),age),>,Property(Ident(m),
age)))),Ident(m),Tuple(List(Property(Ident(w),name),
BinaryOperation(Property(Ident(w),age),-
,Property(Ident(m),age)))))))
@vonjuliano

14.
@vonjuliano

15.
FlatMap(Entity(Couple,None,List()),Ident(c),FlatMap(Entity(Pe
rson,None,List()),Ident(w),Map(Filter(Entity(Person,None,List(
)),Ident(m),BinaryOperation(BinaryOperation(BinaryOperation
(Property(Ident(c),her),==,Property(Ident(w),name)),&&,Binary
Operation(Property(Ident(c),him),==,Property(Ident(m),name))
),&&,BinaryOperation(Property(Ident(w),age),>,Property(Ident
(m),age)))),Ident(m),Tuple(List(Property(Ident(w),name),
BinaryOperation(Property(Ident(w),age),-
,Property(Ident(m),age)))))))
SELECT w.NAME,
w.age − m.age,
FROM couples c,
people w,
people m
WHERE c.her = w.NAME
AND c.him = m.NAME
AND w.age > m.age
+
=
@vonjuliano

16.
ABSTRACTING OVER VALUES
@vonjuliano

17.
val range = quote {
(a: Int, b: Int) =>
for {
u <- query[Person]
if (a <= u.age && u.age < b)
} yield {
u
}
}
db.run(range(10, 20))
@vonjuliano

18.
val range = quote {
(a: Int, b: Int) =>
for {
u <- query[Person]
if (a <= u.age && u.age < b)
} yield {
u
}
}
db.run(range(10, 20))
@vonjuliano

19.
val range = quote {
(a: Int, b: Int) =>
for {
u <- query[Person]
if (a <= u.age && u.age < b)
} yield {
u
}
}
db.run(range)(min, max)
@vonjuliano

20.
ABSTRACTING OVER A PREDICATE

21.
val satisfies =
quote {
(p: Int => Boolean) =>
for {
u <- query[Person] if (p(u.age))
} yield {
u
}
}
db.run(satisfies((x: Int) => 20 <= x))
@vonjuliano

22.
val satisfies =
quote {
(p: Int => Boolean) =>
for {
u <- query[Person] if (p(u.age))
} yield {
u
}
}
db.run(satisfies((x: Int) => 20 <= x))
@vonjuliano

23.
COMPOSING QUERIES
@vonjuliano

24.
val ageFromName = quote {
(s: String) =>
for {
u <- query[Person] if (s == u.name)
} yield {
u.age
}
}
quote {
(s: String, t: String) =>
for {
a <- ageFromName(s)
b <- ageFromName(t)
r <- range(a, b)
} yield {
r
}
}
@vonjuliano

25.
val ageFromName = quote {
(s: String) =>
for {
u <- query[Person] if (s == u.name)
} yield {
u.age
}
}
quote {
(s: String, t: String) =>
for {
a <- ageFromName(s)
b <- ageFromName(t)
r <- range(a, b)
} yield {
r
}
}
@vonjuliano

26.
DYNAMICALLY GENERATED QUERIES
@vonjuliano

27.
sealed trait Predicate
case class Above(i: Int) extends Predicate
case class Below(i: Int) extends Predicate
case class And(a: Predicate, b: Predicate) extends Predicate
case class Or(a: Predicate, b: Predicate) extends Predicate
case class Not(p: Predicate) extends Predicate
def eval(t: Predicate): Quoted[Int => Boolean] =
t match {
case Above(n) => quote((x: Int) => x > lift(n))
case Below(n) => quote((x: Int) => x < lift(n))
case And(t1, t2) => quote((x: Int) => eval(t1)(x) && eval(t2)(x))
case Or(t1, t2) => quote((x: Int) => eval(t1)(x) || eval(t2)(x))
case Not(t0) => quote((x: Int) => !eval(t0)(x))
}
@vonjuliano

28.
sealed trait Predicate
case class Above(i: Int) extends Predicate
case class Below(i: Int) extends Predicate
case class And(a: Predicate, b: Predicate) extends Predicate
case class Or(a: Predicate, b: Predicate) extends Predicate
case class Not(p: Predicate) extends Predicate
def eval(t: Predicate): Quoted[Int => Boolean] =
t match {
case Above(n) => quote((x: Int) => x > lift(n))
case Below(n) => quote((x: Int) => x < lift(n))
case And(t1, t2) => quote((x: Int) => eval(t1)(x) && eval(t2)(x))
case Or(t1, t2) => quote((x: Int) => eval(t1)(x) || eval(t2)(x))
case Not(t0) => quote((x: Int) => !eval(t0)(x))
}
@vonjuliano

29.
EXAMPLE
@vonjuliano

30.
@vonjuliano

31.
A PRACTICAL THEORY OF
LANGUAGE-INTEGRATED QUERY
WITH QUILL
JULIANO ALVES
@vonjuliano
THANK YOU!

32.
Q U E S T I O N S ?
@vonjuliano